Email deliverability is the obstacle between you and your audience. 21% of emails never arrive at your recipients' mailboxes, according to Sendgrid.

If you don’t have good email deliverability, your contacts won’t be receiving your email messages, reducing the effectiveness of your email marketing campaigns. If not monitored carefully, it could go on to affect your ability to send any marketing email at all. 

According to experts, a healthy email deliverability rate sits around 95% and higher.

In this article, you’ll find out how to improve email deliverability and maintain a good rate with:

The best way to improve email deliverability is to make sure your email data is clean. We clean data for you—want to see how? Book a demo with us today.

What is the definition of email deliverability?

Email deliverability can be defined as the number of emails that arrive in contacts’ mailboxes compared to how many emails you send out.

It is usually reported as a percentage, and the higher the number, the better your email deliverability. 

Download our 16-point checklist to stop easily avoidable email deliverability issues

What affects email deliverability?

Email deliverability can be affected by a number of things, including:

  • Your sender reputation

  • The content of your emails

  • Your email marketing service

  • The source of your email contact

Why are some of my emails not being delivered?

There are 3 key things you can do to better understand your email deliverability:

Email bounce rate

An email bounce rate reflects when an email is not being sent to the recipient due to problems with the email service provider.

There are two types of bounce: soft bounce, and hard bounce. 

A soft bounce is due to a temporary issue, such as an inbox being full or the server is temporarily down. The email send is usually attempted a number of times before giving up.

A hard bounce is permanent, once you have an email result in a hard bounce, you can no longer email that recipient. This is usually managed by your email marketing tool. 

It happens when:

  • The mailbox is inactive or no longer exists,

  • There’s a mistake in the email address, or when

  • Your IP address is considered to have too low a reputation.

graph showing average bounce rates by company size

It could have an effect on your overall email deliverability rates, as frequent hard bounces can result in your IP address being blacklisted. Campaign Monitor recommends that you keep your bounce rate under 2%.

Email list health and hygiene

Email list hygiene is about how good a shape your email contact lists are in. A healthy list has:

  • Contacts you have gathered yourself, who have given you express permission to contact them (if they’ve given a double opt-in, even better)

  • A good churn rate (the rate at which people unsubscribe)

  • Good open rates (CampaignMonitor says 15-25% is the average)

  • Low bounce rates (no higher than 2%)

Email deliverability test 

There are a number of tools you can use to test your deliverability and can help you identify potential issues that might affect your email send.

Tools such as Spamhaus and Spamcop scan major spam blacklist databases. MailPoet’s free Mail Tester tool analyzes the message, your mail server, and your sending IP and sends you a report of what's configured properly and what isn’t.

Most email marketing services have this built into their service during the sending process, or integrate with tools that allow you to run your emails through a test before sending.

Email deliverability best practices

1. Avoid spam filters

Spam filters are used by most email service providers and might block your emails from arriving in a subscriber’s mailbox for a number of reasons.

It is designed to catch unwanted and potentially dangerous emails, based on certain criteria. However, despite our best efforts, legitimate marketing emails can be caught by these filters and prevented from landing in our contact’s inbox.

The main things you can do are covered in the rest of this article, such as keeping your list clean and ensuring you have the right authentications.

People may mark your email as spam, and this flags concerns to email service providers when it comes to delivering your next email campaign. This could be for many reasons. In fact, 43% of people mark emails as spam just because they can’t easily locate the unsubscribe link or the process is too difficult.

To bring the changes of this happening down, don’t give your subscribers a reason to hit the spam button, or consider your email to be ‘spammy’. This means the content should look like a professional marketing email and should be relevant to your audience.

2. Email Authentication

Email authentication or email validation is a set of standards you can set up to verify that your email is legitimate, and coming from who it claims to come from. Email authentication is usually used to block phishing and spam emails who use fraudulent methods to send mass emails.

The most commonly used email authentication standards are SPF, DKIM, and DMARC, which you need to configure with your DNS (Domain Name System) records.

Setting up your basic set of authentication standards requires you to add four DNS records to your DNS hosting provider for the domain you wish to send from. The domain or domains you wish to authenticate must be used in your email sender list. 

This set-up can be done within your email marketing provider, and the process may vary from tool to tool.

  1. MX Record: This is what allows you to deliver email to your domain. The Mail Exchange (or MX) records check the mail servers and identify which accept incoming email for your domain. 

  2. SPF (Sender Policy Framework) Record: A TXT record that allows you to specify which IP addresses are authorized to send email from your domain.

  3. DKIM (Domain Keys Identified Mail) Record: A TXT record that allows your email tool to verify emails sent on your behalf. The DKIM signatures ensure that your recipient receives the same message in their inbox as the one you sent from your email tool.

  4. DMARC (Domain-based Message Authentication Reporting and Conformance) Record: This allows Internet Service Providers (ISPs) to prevent fraudulent or malicious email practices, such as domain spoofing. It enables email senders to specify how to manage emails that were not authenticated using SPF or DKIM.

Doing this is worthwhile to ensure that your emails have the best chance of being identified as legitimate and getting through to your contacts. It can also increase the success of your marketing programs, see the chart below.

types of email authentication tools for reducing email bounce rate

3. Use a dedicated IP address

Most of the larger email service providers, such as Mailchimp, CampaignMonitor, or Hubspot provide a shared IP (internet protocol) as default. In this case, the email sender reputation is made up of an aggregation of reputations from all of their users on the same IP. Email service providers manage their domain reputation, and maintain high rates, to ensure that their clients don’t suffer through the fault of another email sender.

Using a dedicated IP address allows you to have a single IP address just for your domain. This is useful in the case that you send a lot of emails (over 100,000 messages a week). If you are a high volume sender with good engagement from your emails, a dedicated IP gives you more control over your email sends. Most email service providers offer this as an add-on to their enterprise packages.

4. Use a dedicated subdomain for email marketing

A subdomain is the prefix to your domain. For example, the ‘maps’ part of 

Using a subdomain as the domain you send emails from adds a layer of protection to your sender reputation or sender score. By using different subdomains for each type of email that you send, for example, having a dedicated subdomain for support and another for marketing means any mistakes or red flags that occur on one, won’t affect the sender reputation of the other.

If you send mail globally, this can be useful to separate out your mails by region or country. 

In this example from retailer Urban Outfitters, their rewards program emails are sent from and their feedback surveys from

As well as these email deliverability best practices, there are other important elements of email sending that can help improve the overall deliverability rates such as email list management and improving your email marketing content.

Email deliverability: staying out of the spam box

5. Keep your email list clean for better email deliverability

Good list hygiene is essential for keeping your email delivery rates high. It ensures the people you are emailing are engaged, can be segmented into personalized email campaigns, and have granted you permission to email them. 

Emailing ‘the wrong’ contacts (in this case unwanted and unengaged contacts) can result in a poor sender reputation, disappointing open rates, and possible spam complaints. All of these things go on to continue giving your email deliverability issues, so it’s best to start with a strong, healthy list to avoid these risks.

Cleaning your data doesn’t need to be an arduous task. We’ve calculated that a single contact point takes an average of 3 minutes to clean, so if your contact lists are on the smaller side, you may need to dedicate a few days to do this. If you’re working with larger lists, then consider using a data cleaning tool.

Here’s what to look for when cleaning your contact lists:

  • A contact that frequently soft bounces
  • A contact who has hard bounced
  • A contact who rarely, or never opens your emails
  • Contacts that did not opt-in (perhaps you were given or bought the email list)

A contact that fits into any of these categories should be removed from your send lists.

Email deliverability is key to success with email campaigns. Here are 13 ways to maintain a high deliverability rate and see better results with email marketing in 2020. #EmailMarketing 

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6. Monitor user engagement

When contacts continually don’t engage with your emails, it may affect your sender reputation and your ability to send emails. Monitor this number over time, and consider what tactics you could implement to re-engage your subscribers.

If the issue is with a low open rate (the average is between 15%-25%) then consider how you could get your contacts to start opening your emails. This could be experimenting with subject lines (use coschedule to test them) or changing your sender name.

If you are seeing a low or non-existent click-through rate (the average is 2.5%), then you need to adapt the content within your email. Do you need a new designer? Have you experimented with buttons vs hyperlinked text?

If these problems persist or start to dip below average for your contacts then you need to start filtering them out, before they affect your email deliverability.

7. Filter on engagement

Inactive contacts harm your email marketing campaigns. Not only could they affect your sender reputation and therefore email deliverability, but they make your marketing reports look bad too. The best solution? Filter them out, and stop sending them email.

Filtering by engagement can be done within your email marketing tool and involves creating a workflow to identify which contacts are not engaging. You can do this by specific campaigns or lists, or by overall engagement. It’s best to compare timescales, such as over the past year vs over the past month, to identify trends.

Inactive contacts harm your email marketing campaigns. The best solution? Filter them out, and stop sending them email. #EmailMarketing  #DataCleaning

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Once you have these lists, you can suppress them, which means you stop them from receiving emails without deleting them entirely, or you can try a specialized re-engagement campaign.

Here’s an example of a re-engagement email from Animoto.

The goal of this email is to get contacts to either adapt email type or frequency to better suit them (and remind them why they subscribed in the first place), or unsubscribe completely.

This results is either a more engaged contact or a cleaner list, win-win.

8. Create a sunset policy

Once you’ve done your initial cull of inactive contacts, you want to turn this into ‘business-as-usual’ task, to keep your lists consistently healthy.

Creating a policy whereby you routinely clear out contacts that meet specific criteria allows you to keep your lists healthy, and only send to engaged subscribers.

The criteria is usually based around the amount of activity (or lack of) over a period of time. Such as, any contacts who haven’t opened a newsletter in 3 months.

Email content best practices

9. Email content

The content of emails should not be overlooked by email marketers. The more professional-looking and relevant your email, the less likely it is to end up in a spam folder. 

Your email content is not just important for the recipient, but for email service providers too. If they consider your email to originate from a spammer, or to contain too many ‘spam’ like qualities, you may not make it past the spam filters.

‘Spam’ like qualities include:

  • Attachments

  • Very large files such as images or videos

  • No subject line

  • Very short emails/lack of text

  • Links that point to unsecure websites

10. Test your emails

Once you’ve crafted the perfect email, don’t forget to test it to ensure it’s having the reaction you wanted. 

A/B testing allows you to send two versions of the same email to a small subset of your email list, once your email provider has enough data from this initial send, it sends the ‘winning’ email to the remainder of the list. The ‘winner’ is the highest performing email, picked on a range of engagement metrics.

It’s best to test just one alternative element at a time so that you know what has made it more effective.

11. Personalize emails

Ensuring your content is relevant to your audience relies on personalization. Personalizing your marketing emails allows you to be specific with your message, so that you can get to the root of your contact’s pain points or desires, in order to help them convert.

Not only will this decrease the likelihood of being dismissed as irrelevant and being marked as spam, but it can have a positive effect on sales too. According to Accenture, 91% of people are more likely to buy from companies that send personalized emails.

12. Consider who your email is coming from

Most email marketing tools allow you to use different sender names for your email campaigns.

The benefits of this are that when you consistently send emails from the same sender name, you can establish a relationship, whereby the contact expects your email and knows what kind of content will be inside.

Using a ‘human’ name works well, and allows you to make the message feel more conversational and relatable. You can use sender names in a variety of ways across your campaigns:

  • Send key emails about the company, such as big changes or yearly updates from your CEO

  • Product marketing campaigns should come from your Product Manager

  • ‘Top Tips’ and best practice campaigns should come from the person most closely related to this area, for example, an email campaign on ‘converting leads’ should come from your Head of Marketing

13. Send consistently

Frequent, routine emails create a familiarity with your subscribers. It keeps the conversation open and allows you to create a relationship with them.

However, what is welcomed by one subscriber might be considered too much for another. Allow your subscribers to select the frequency at which your emails are sent to them, whether it’s a weekly update or a monthly newsletter.

Tired of your emails going into spam, even if you aren't doing
anything spammy?

Get our 16-point email deliverability checklist to protect your sender reputation.

Email deliverability testing tools

Using email deliverability testing tools is the final step in ensuring that your emails are going to arrive in your subscribers’ inboxes.

There is a range of email deliverability software out there. 

I’ve already mentioned Spamhaus and Spamcop which scan major spam blacklist databases.

Always Arrive, GlockApps or Spamcheck by Postmark analyze the content of your emails as well as your sender reputation. They are simple to use and involve either posting a link, or sending an email to a specific address. It then generates your ‘results’ and highlights what’s good, and what might be affecting your deliverability.

The best way to improve email deliverability is to make sure your email data is clean. We clean data for you—want to see how? Book a demo with us today.

Are you going to implement any of these tips? Share your best suggestions for maintaining good email deliverability rates in the comments.

Markus Beck

Markus Beck - February 25, 2021

CEO with a passion for data relationships. Markus is half Finnish, half Austrian & fully committed to helping businesses keep bad data from ruining great relationships. Process Engineer by training, with digital marketing & project management skills from previous jobs.